Specifies the minimum protocol version. This can be one of: LDAP_OPT_X_TLS_PROTOCOL_SSL2,LDAP_OPT_X_TLS_PROTOCOL_SSL3, LDAP_OPT_X_TLS_PROTOCOL_TLS1_0, LDAP_OPT_X_TLS_PROTOCOL_TLS1_1, LDAP_OPT_X_TLS_PROTOCOL_TLS1_2

Specifies the certificate checking checking strategy. This must be one of: LDAP_OPT_X_TLS_NEVER,LDAP_OPT_X_TLS_HARD, LDAP_OPT_X_TLS_DEMAND,
LDAP_OPT_X_TLS_ALLOW, LDAP_OPT_X_TLS_TRY.
(Available as of PHP 7.0.0)